Vehicles may be equipped with lifting mechanisms such as ramps and chairlifts for facilitating access of a physically impaired person using a mobility device such as a wheelchair. In response to a command by an operator, a ramp may be lowered from an open vehicle door to reach a pavement. Once the ramp has been used by the passenger to board the vehicle, the ramp may be folded and stowed under the floor of the vehicle cabin. Power from an on-board hydraulic system and/or an electric motor may be used for operating the lifting mechanism. Engine power may be used to charge an on-board battery supplying power to the hydraulic system and/or the electric motor.
Various approaches are provided for operating a lifting mechanism in a vehicle. In one example, as shown in US20100332085, Song et al. teaches operation of a power ramp coupled to a vehicle. The power ramp is operated via a power generating device comprising a motor gear coupled to the ramp. The power ramp may be operated upon confirmation that the vehicle is stopped and is parked. Also, the operation of the ramp may be inhibited if the vehicle door is not opened.
However, the inventors herein have recognized potential issues with such systems. As one example, during an engine idle-stop, when the engine combustion is disabled, operation of the lifting mechanism may be requested and the state of charge (SOC) of a battery providing power to the lifting mechanism may not be sufficient for operating the lifting mechanism, thereby delaying operation of the lifting mechanism. Also, in the system of Song et al., during an engine idle-stop even if the vehicle is at rest, the lifting mechanism may not be operated if the vehicle is not at park (such as when the transmission position is not park). When the vehicle is parked on a slope, even with the transmission at park, the vehicle may roll and may not be stable enough to operate the lifting mechanism. If engine idle-stop conditions are met and a request for operation of the lifting mechanism is received, the engine may shut down without providing the power needed for operating the lifting mechanism, thereby delaying operation of the lifting mechanism.
In one example, the issues described above may be addressed by a method for a vehicle comprising: responsive to a driver request for operating a lifting mechanism coupled to the vehicle received while an engine is at rest, shifting a transmission into a park position, restarting the engine, and then operating the lifting mechanism. In this way, engine idle-stop operations may be better coordinated with the operation of a lifting mechanism.
As one example, a lifting mechanism may be coupled to a body of a mobility vehicle, the lifting mechanism enabling a passenger using a mobility device (such as wheelchair) to enter and exit the vehicle. The lifting mechanism may be actuatable vertically and/or horizontally relative to the body of the vehicle. In response to engine idle-stop conditions being met (such as in response to a longer than threshold duration of engine idling), an engine idle-stop may be initiated wherein cylinder combustion may be temporarily suspended and the engine is spun to rest. During engine rest, if operation of a lifting mechanism is requested while the vehicle is stationary, such as to load or unload a wheelchair-bound passenger, the controller may automatically restart the engine in order to charge an electric battery used for supplying power to the lifting mechanism. If the transmission of the vehicle is not at park, before restarting the engine, the transmission gear may be shifted to park so that the vehicle can be held at rest. Further, before restarting the engine, the electronic park brake may be engaged before operating the lifting mechanism. Once it is confirmed that the vehicle is at rest, the transmission is at park, the electric parking brake is enabled, and the engine has been restarted, the lifting mechanism may be operated. During the engine restart, the electric battery may also be used to operate the starter motor to crank the engine. During engine cranking, if operation of an auxiliary vehicle system, such as the air suspension system, is also requested, the operation of the auxiliary system may be delayed until the engine cranking is complete (e.g., until the engine speed is at or above a target cranking speed). If the request for operating the lifting mechanism is received prior to the engine idle-stop being initiated, even if all other idle-stop conditions are met and the vehicle is at rest, the engine idle-stop may be temporarily overridden and engine operation may not be stopped. Instead, the transmission gear may be shifted to park and the electronic park brake may be enabled so that the lifting mechanism can be operated. Once operation of the lifting mechanism is completed, the engine idle-stop may be resumed, the transmission may be shifted out of park (e.g., to a default idle-stop position or the position it was in prior to the receiving the request for operation of the lifting mechanism), and the electronic parking brake may be disabled.
In this way, operation of a lifting mechanism may be coordinated with engine idle-stop and restart events so as to give priority to the operation of the lifting mechanism. In response to a request for operation of a lifting mechanism received during an engine idle-stop, by first shifting the transmission gear position to park, via an engine controller, before operating the lifting mechanism, the possibility of vehicle movement during operation of the lifting mechanism may be reduced. By also engaging the electronic park brake before operating the lifting mechanism, even if the vehicle is parked on a slope, rolling of the vehicle may be reduced. By resuming the original transmission position after operation of the lifting mechanism is completed, vehicle operation may be seamlessly resumed. The technical effect of actively restarting an engine from an idle-stop in response to a request for operation of a lifting mechanism is that engine power may be used to effectively operate the lifting mechanism. By restarting the engine, reliance on battery state of charge during operation of the lifting mechanism may be reduced. By delaying engine shutdown even when the conditions for an engine idle-stop are met, operation of the lifting mechanism may be expedited. By postponing operation of any auxiliary vehicle system such as the air suspension system during engine cranking, the battery charge may be used to efficiently crank the engine within a shorter time and to start operating the lifting mechanism. In this way, a lifting mechanism may be operated while engine start-stop operations are performed to improve vehicle fuel economy.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.